A unit of this kind is known from the European patent EP-A-0578602, issued to the applicant, wherein a principle is used for the upright positioning of the containers which is known from the U.S. Pat. No. 3 295 659 and is based on a circling of the containers arranged in a lying position inside peripheral cavities in such a way that the container body is supported by a stationary annular shelf interposed between the open bottom of said compartments and said discharge chutes, the neck of the container being held by holding members provided next to the bottom of said moving compartments. The orientation in an upright position is achieved by means of providing an interruption in said stationary annular shelf supporting the container body, this determining the falling of the container into the corresponding discharge chute with its bottom first since regardless of the position of the container in the compartment its neck or upper filling part is being held by said holding members.
This orientation system presents nevertheless the drawback that at the beginning of the positioning there is always a critical transfer from a stationary support, i.e. the above-mentioned annular shelf, into a moving part, i.e. the aforesaid discharge chutes, with the risk that during said transfer and due to the light weight of the containers, to the possible irregularities of the latter, etc. jams might possibly occur, with the consequent damage to the containers and undesired shutdowns of the unit.
A second drawback related to the precited upright positioning technique derives from the limitation imposed by said structure since it needs a specific area where the positioning of the containers has to take place as they fall, this having to occur at a point sufficiently distant from the loading area, which in some units has required to split the falling process in two parts in order to give the containers the time needed for them to reach the bottom of the discharge chutes to thereupon be driven on a stationary flor up to an out feed conveyor; see for example patent U.S. Pat. No. 3,650,368 and U.S. Pat. No. 4,130,194, this latter comprising peripheral cavities to hold the containers.
From patent U.S. Pat. No. 4,949,834 is on the other hand known a unit whose general characteristics are equivalent to those of the aforementioned patent U.S. Pat. No. 4,130,194 but wherein although the positioning of the containers is equally achieved by means of a transfer from a slidingly resting position on a stationary annular shelf into a moving part formed by the discharge chutes elements associated to said discharge chutes have been provided which in the absence of said stationary shelf give an ulterior support to a preestablished part of the container, in such a way that the upright positioning of the latter is produced and completed as it falls into the discharge chute.
For such a purpose an automated positioning of said supporting element has been provided by means of using means for recognizing the previous position adopted by the containers inside said peripheral cavities, said elements being actuated as dictated by said previous position as per a conventional technique used in the field of the conveying and storing of goods and described, for example, in the publications of prior art: ES-A-8203775, ES-8205702 and EP-A-0242214, for similar applications.
Although the solution described in the aforesaid patent U.S. Pat. No. 4,949,834 allows to employ peripheral cavities of big dimensions allowing to process containers of various shapes and sizes, the technical doctrine described in said patent does still present the drawbacks deriving from the aforementioned positioning/orienting principle, i.e. the transfer takes place from a slidingly resting position on a stationary part into a moving part, with the added drawback that the supporting means aiding the positioning are precisely provided in said moving part, this resulting in the fact that although it is possible to achieve a correct automated positioning of said supporting elements there is an evident risk that the proper positioning of the containers cannot be finally attained. Said supporting elements have to be besides returned to their starting position by means of using stationary and moving stops, which implies a considerable mechanical complexity. The use of stops entails besides the generation of noises, and their effect upon the return to origin can generate overstresses and errors.
Due besides to the fact that the support is formed in the aforementioned discharge chutes it is not possible to proceed to an eventual change of said discharge chutes as could be necessary when the unit is used to process containers of very different shapes or sizes.
Besides, the use of a stationary supporting shelf interposed which when interrupted provides the fall of the containers impose the limitation that the unloading of the machine should be done in a fixed zone.